As is generally known, a conventional safety device provided in a passenger car to protect occupants of the car from an impact occurring during a collision comprises an air bag, and a gas generator for inflating the air bag in a very short period of time.
This gas generator has, as main constituent elements, a centrally positioned igniter in which a squib/enhancer is held, a cylindrical combustion chamber formed about the igniter and housing gas generants therein, and a cross-sectionally rectangular filter/coolant chamber formed about the combustion chamber wherein a gas generated in the combustion chamber passes through a filter and a coolant and flows through gas outlet ports into an air bag.
Various types of structures wherein a housing forms a combustion chamber and a filter/coolant chamber for a gas generator have heretofore been proposed.
For example, a pressure container is used which consists of a case formed by subjecting a stainless plate to press working, and then welding the case at bolts set at the central portion thereof, and at rivets set at the circumferential portion and the outer circumferential portion thereof. The container for gas generants disclosed in U.S. Pat. No. 4,547,342 (Morton Thiokol, Inc.) consists of upper and lower halved shell bodies, and partition walls for forming three cylinders in the halved shell bodies.
Japanese Patent Publication-A No. 152639/1980 (Bayern Chemie GmbH.) discloses a gas generator having a central cylinder holding an igniter therein, a cover and an S-shaped casing which form a combustion chamber and a filter chamber. Outlet ports of the filter chamber (expansion chamber) are formed in an extended portion of the casing by punching slits therein.
However, in order to incorporate any of these conventional gas generators in a steering wheel of an automobile, it is necessary that the thickness of the wall, particularly the wall which faces a driver, of the housing at the combustion chamber be made large, and this causes the weight of the housing to increase. Moreover, since the sealing of the gas generants is done by welding, a gas generator assembly line and the equipment required become complicated.
An object of the present invention is to provide a gas generator of a weight-reduced structure having a housing with a thin plate sealed by a non-welding method, which is advantageous with respect to the manufacturing equipment required to manufacture the generator.